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We have 3 switches at the moment - see the diagram below for NOW. Essentially the CORE switch is 7, and 8 and 9 have a 3 cable trunk each to 7.

Now, we want to add Switch 5 to the equation - see AFTER - would this be a suitable way of configuring the trunks. Or create a new trunk on Switch 8 and Switch 9 (say Trk3 and Trk4) rather than creating Trk1 and Trk2 on Switch 5 and taking one cable from the existing Trk1 and Trk2 on Switch 8 and 9 respectively and connecting to Trk1 and 2 on Switch 5. Do the names and groups actually make a difference if connected to different switches.

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Rex
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PnP
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1 Answers1

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You can't do this unless switches 5 and 7 are stacked together. You can't form a single HP link aggregated trunk group from one switch to two separate switches.

You will need to create new trunk groups on 8 and 9 to trunk to switch 5. Technically, you can still use trk1 and trk2 as the names of trunk groups on switch 5.

Rex
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  • Hi Rex, when you say Switch 5 and 7 are stacked together? – PnP Jun 16 '14 at 20:57
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    Well, you haven't said what model switches you have, but stacking switches (Cisco/HP/whatever) is usually done through a specific stacking module/uplink to enable to the two switches to share a common backplane and allows the members of the stack to be managed as a single unit. See Wikipedia's definition of it: http://en.wikipedia.org/wiki/Stackable_switch – Rex Jun 16 '14 at 21:00
  • My experience with HP switches was that "stacking" them puts them in a unified configuration interface only - they don't have any short of shared backplane, just ethernet connections. It wouldn't allow you to do link aggregation across multiple switches, like you would with a (cisco-definition) stackable switch where the switches are connected via a high speed backplane connector. This was pre-H3C acquisition, i have no experience with the original H3C switches, just the original HP procurve stuff. I haven't touched an HP switch in over 2 years. – Dan Pritts Jun 16 '14 at 21:38
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    @DanPritts - There are quite a few HP switches that are able to be configured as a true stack with dedicated stacking modules with a dedicated shared backplane to allow link aggregation across stack members. – Rex Jun 16 '14 at 21:43
  • good to know. I presume though that some of them still have the software-only stacking feature? – Dan Pritts Jun 16 '14 at 22:01
  • @DanPritts Not really anymore. The old e-series switches were mgmt only stacking. Any of the newer switches that support any of the stacking technologies (IRF, HP Mesh, or dedicated stacking modules) will support link aggregation across stack members. – Rex Jun 16 '14 at 23:02
  • Actually, I take that back, Apparently the HP4210 still has the management only piece connecting multiple legacy Comware based legacy devices. – Rex Jun 16 '14 at 23:14